Method for producing a head element for heaters

ABSTRACT

According to a method for producing head elements for heaters, a piece of sheet metal ( 1 ) is deep drawn and cut along the edge ( 9 ) of an open side ( 6 ) to obtain a hollow body ( 8 ) with larger and narrower sides ( 4,5,14,15 ). An aperture ( 12 ) is made on each opposite larger side ( 4,5 ) of the hollow body, and threaded rings ( 26 ) are then applied around the lateral through apertures ( 12 ). Notches ( 16 ) are made on the opposite large sides ( 4,5 ), along the edge ( 9 ) of the open side ( 6 ), and then three cores ( 18 ) are introduced through the edge ( 9 ), so that a flange ( 17 ) around the notches ( 16 ) can be made by pressing, so as to close the sheet metal ( 1 ) around the cores ( 18 ) widening the notches ( 16 ). After the cores ( 18 ) have been removed, the edge ( 9 ) is welded along the flange ( 17 ) of the widened notches ( 16 ), thus obtaining holes ( 21 ) separated from each other.

FIELD OF THE INVENTION

[0001] The present invention relates to the production of heaters.

[0002] In particular, the present invention relates to the production ofhead elements used for supporting and connecting the tubular heatingelements, which form the heater.

DESCRIPTION OF THE PRIOR ART

[0003] According to known methods, heaters for e.g. civil and industrialuse are produced by joining tubular elements using head elements, whichsupport and join the tubular elements with each other.

[0004] The groups, composed of two or more tubular elements joined oneto another by head elements, are connected to each other by liquid-tightconnection applied between each pair of head elements, thus forming aheater.

[0005] There are different methods for producing the head elements.

[0006] The Patent Publication FR 1.201.614 describes the preparation ofthe head element by fusion technique and subsequent working of the soobtained workpiece.

[0007] The obtained head element is composed of a hollow body with fourparallel holes situated on a narrow and long side of the body andcommunicating with the inside, and of two opposite apertures made on thetwo wider surfaces of the body.

[0008] The four parallel holes are machined inside while the oppositeapertures are threaded internally.

[0009] Subsequently, two head elements are applied to the oppositeextremities of four tubular elements by introducing and fastening, bywelding, the tubular elements ends into the four parallel holes.

[0010] Threaded joints are inserted into the opposite and threadedapertures of the head elements so as to connect the thus obtained groupsto each other.

[0011] According to the document FR 1.425.677, the tubular elements arejoined to the head elements by an adhesive.

[0012] The drawbacks of the head elements obtained in this way derivefrom the difficulty in producing, by fusion, a head element which ishollow and features holes of small diameter conducting to the cavity.

[0013] This constructive feature imposes the use of cores, which must becrumbled in order to be removed from the piece obtained by fusion, thusincreasing the number of working steps and production costs.

[0014] Moreover, it is difficult to make the fused material flowappropriately in the dies to avoid a high number of wastes.

[0015] This problem imposes also the choice of those materials whichfeature good flowability when fused, in place of other materials, whichwould be cheaper, but are more difficult to be treated by fusion.

[0016] The publication EP-A-0854347 describes a method for obtaininghead elements, which have an aperture on their narrow side, opposite tothe side with holes for connection with the tubular elements.

[0017] This conformation allows insertion of a suitably shaped core intothe die during the fusion, to support easily the core and to remove itwithout the necessity of subsequent operations for cleaning andfinishing of the inner cavity.

[0018] However, it is necessary to close the aperture before assemblingthe tubular elements.

[0019] According to another known method, the head elements are obtainedby pressing two semi-shells of e.g. sheet metal, and welding the twosemi-shells along their whole contour.

[0020] In this way, the head element is produced from a cheap material,e.g. a ferrous material, using a procedure that is not particularlycomplicated, such as fusion.

[0021] Nevertheless, the welding of the two semi-shells is verydifficult, because of the welding length and critical position, as itextends along the matching line of the two curved surfaces and must passacross further curved sections.

[0022] Since the head element must be liquid-tight, so the welding mustbe performed correctly, thus increasing the difficulty and costs of thisworking operation.

[0023] Moreover, after the welding had been finished, it is necessary tofinishing the whole welded area, in order to make it shapely.

[0024] This step increases again the production time and costs.

SUMMARY OF THE INVENTION

[0025] The object of the present invention is to propose a method forproducing a head element composed of one single body, by more pressingsteps, without the drawbacks resulting from the fusion procedure andwithout the necessity to weld other closing elements of the headelement.

[0026] Another object of the present invention is to propose a method,which allows a reduction of time and costs of the head elementproduction.

[0027] A further object of the present invention is to propose a method,which allows using ferrous material, which is cheap and easy to work.

[0028] A still further object of the present invention is to propose ahead element obtained by the above mentioned method, whose production ischeap and does not require extensive time, and which is shapely, so asto reduce as much as possible other finishing operations.

[0029] In particular, the proposed head element is produced in such away that it does not require grinding of extended surfaces, which havebeen welded in critical points.

[0030] The above-mentioned objects are obtained by a method forproducing head elements for heaters, characterized in that it includes:

[0031] preparing of a piece of a sheet metal;

[0032] deep drawing said sheet metal piece to obtain a hollow moldedpiece, defined by a base wall, sides joined to and surrounding the basewall and forming an open side;

[0033] cutting the sides along the open side, to define a hollow bodywith an edge, which is uniform and extends around said open side;

[0034] making a lateral through aperture on two opposite sides to obtainapertured opposite sides;

[0035] providing connection means around each lateral through aperture;

[0036] making of at least one notch, on the apertured opposite sides,along said edge;

[0037] introducing at least two cores into said edge matching areaswithout said at least one notch;

[0038] stamping a flange extending around each of said at least onenotch and included between said cores, so as to close the sheet metalaround said cores and in the area of said edge, thus widening saidnotches;

[0039] removing said cores from the hollow body;

[0040] welding of said edge along said flange of said widened at leastone notch, so as to obtain a series of holes separated from each other.

[0041] According to a different embodiment of the method for producingthe head elements after the hollow body is obtained the following stepsare performed:

[0042] making a lateral through aperture on each two opposite sides toobtain two apertured opposite sides;

[0043] making at least one notch, on each of said apertured oppositesides, along said edge;

[0044] introducing at least two cores into said edge in areas withoutsaid at least one notch;

[0045] pressing a flange extending around said notches and includedbetween said cores, so as to close the sheet metal around said cores andin the area of said edge, thus widening said notches;

[0046] removing said cores from the hollow body;

[0047] welding said edge along said flange of said widened at least onenotch, so as to obtain holes separated from each other;

[0048] providing fastening means on each lateral through aperture oneach of said apertured opposite sides.

[0049] From the method a head element for heaters is obtained, which ismade in a single hollow body, defined by a base wall, sides joined toand surrounding the base wall, at least two holes turned toward theinside of said hollow body, with at least one lateral through aperturemade on two opposite sides defining two apertured sides, characterizedin that:

[0050] said body is obtained from a single part of a deep-drawn metalsheet;

[0051] said holes are delimited by a press-shaped edge of an open side,opposite to said base wall of said hollow body, with notches made onsaid edge and widened by pressing, so as to define pressed flanges,which surround the notches and are welded to each other to separate saidholes; and

[0052] fastening means are provided on each lateral through aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In accordance with the invention, the head elements and themethod of its production are defined by the characteristic featuresreported in independent claims concerning the product and the method,respectively, and other preferred characteristic features reported inadditional claims.

[0054] In the following, the invention is described in a more detailedway with reference to particular, but not only embodiments and withreference to the enclosed drawings, in which:

[0055]FIG. 1 is a lateral section view of the body of a head elementduring its forming by pressing, according to the present method;

[0056]FIG. 2 is a top view of the body of FIG. 1;

[0057]FIG. 3 is a lateral view of the body of FIG. 1;

[0058]FIG. 4 is a perspective view of the body of FIG. 1;

[0059]FIG. 5 is a view of the body of FIG. 1 in a subsequent workingstep;

[0060]FIG. 6 is a section view of the body along the line VI-VI of FIG.5;

[0061]FIG. 7 is a view of the body of FIG. 5 in another working step ofthe present method;

[0062]FIG. 8 is the body of FIG. 7 along the line VIII-VIII;

[0063]FIG. 9 is a section view of the finished head element;

[0064]FIG. 10 is a view of constructive variant of the body forming thehead element;

[0065] Figures from 11 to 13 show three working steps necessary tocomplete the head element according to the above mentioned constructivevariant;

[0066]FIG. 14 is a view of the finished head element, according to theabove mentioned constructive variant;

[0067]FIG. 15 is a view of two finished head elements, according to theabove-mentioned constructive variant; joined to each other.

BEST MODES OF CARRYING OUT THE INVENTION

[0068] According to the present method, with reference to Figures from 1to 4, head elements for heaters are produced beginning from a piece ofsheet metal 1.

[0069] The piece of sheet metal 1 is first deep-drawn to obtain a hollowmolded piece 2 defined by a base wall 3, two opposite larger sides 4, 5joined to the base wall 3, two narrower sides 14, 15, joined to the basewall 3 and integral with the two opposite large sides 4, 5, and an openside 6, situated opposite with respect to the base wall 2.

[0070] It is assumed that there will be always two larger sides and twonarrower sides, as this is the common practice in manufacturing thesefittings. It is self evident that the method can be equally applied to ahead having equally extending sides, this being also part of the claimedinvention.

[0071] The deep drawing of the sheet metal 1 to obtain the hollow moldedpiece 2, is performed according to a series of subsequent steps, e.g.three steps.

[0072] The intermediate forms assumed by the hollow molded piece 2during the drawing step are indicated with dotted line and broken lingin FIG. 1.

[0073] According to particular materials and dimensions of the headelement to be formed, it is possible to obtain the hollow molded pieceby only one drawing step, without leaving the inventive scope of thepresent invention.

[0074] The deep-drawing step can be performed by using a mechanicalpress or a fluid-pressing device (hydro-forming), or any other suitableapparatus.

[0075] The base wall 3 and the narrow sides 14, 15 can be curved, asshown in FIGS. 2 and 3, or they can have more or less rounded cornersand edges, so that the head element can show a squared form.

[0076] Later, the opposite large sided 4, 5 and the narrow sides 14, 15are cut near the open side 6, along the broken line T of FIG. 3, so asto define a hollow body 8 (FIG. 4), with an edge 9 uniform and oblong,extending around the open side 6.

[0077] A lateral through aperture 12, e.g. circular, is made on each ofthe opposite large sides 4, 5 (FIG. 5).

[0078] The aperture 12 can be made by punching or drilling, the choiceof the technique depending on the materials used and thickness obtained.

[0079] As shown in FIG. 9, fastening means 25 are made on each lateralthrough aperture 12 of each of the opposite large sides 4, 5, so as toallow mutual fastening of the adjacent hollow bodies to assemble groupsformed by the head elements and the tubular elements, thus building aheater.

[0080] According to a first embodiment, shown in FIG. 9, the fasteningmeans 25 on each lateral through aperture 12 are obtained by welding athreaded ring 26 around the lateral through aperture 12.

[0081] A threaded joint (not shown) is then screwed into the innerthreading 36 of the ring 26 during the heater assembly.

[0082] According to another embodiment of the fastening means 25, shownin Figures from 11 to 15, a circular crown 27, extending around eachlateral through aperture 12, is obtained by applying a pressure directedoutwards, thus deforming plastically the hollow body 8 and forming aprotruding edge 31.

[0083] The protruding edge 31 is obtained by introducing a flat core 28into the hollow body 8 through the open side 6, before the holes 13 aremade (FIG. 11).

[0084] The flat core 28 is equipped with a floating element 29, which issituated in a position matching each lateral through aperture 12 and ispushed outwards alternately in opposite directions, thus forming theprotruding edge 31 on the circular crown 27.

[0085] A die 30 is situated on the outer part of the hollow body 8during the pressing on the circular crown 27, to strike as a stopagainst the hollow body 8 and form the protruding edge 31 from outside(FIGS. 12 and 13).

[0086] The protruding edge can be obtained by using a mechanical pressor a fluid-pressing device (hydro-forming).

[0087] At this point the apertures 12 can be finished, e.g. by boring orother suitable known technique.

[0088] A threaded ring 38 can be inserted into the seat defined by theprotruding edge 31.

[0089] The ring 38 fulfills the same function as the ring 26, fastenedexternally in the previously described embodiment, as shown in FIG. 14.

[0090] Otherwise, the adjacent head elements can be joined by weldingspots 37 of the circular crowns touching each other, as shown in FIG.15, using the apertures 12 arranged in a sequence, to enter this area.

[0091] Independently from the used embodiment of the fastening means 25,two notches 16, suitably spaced apart, are made on each of said oppositelarge sides 4, 5, along said edge 9, so as to leave three areas 19 ofthe edge 9 unvaried and without the notches.

[0092] The depth of the notches must be determined by the dimensions ofthe head elements to be obtained and of the holes to be obtained forcoupling with the tubular elements 23.

[0093] In the example case, there are three holes for tubular elements.

[0094] However, the method can be advantageously carried out also with asmaller number of holes, e.g. two, or a bigger number of holes, e.g.four holes.

[0095] The number of the notches 16 to be made on each opposite surface4, 5 depends substantially on the number of the holes and is smaller toit by one.

[0096] Therefore, with two holes to be obtained, it is necessary to makeonly one notch 16 on each surface, while with three holes to beobtained, two notches 16 must be made on each surface.

[0097] Cylindrical cores 18 are introduced into the edge 9, in theregion of to the intact areas 19 (FIG. 7).

[0098] The number of cylindrical cores 18 corresponds to the number ofthe holes 13 to be made.

[0099] In the shown example, three cylindrical cores 18 have beenintroduced.

[0100] The depth of introduction of the cylindrical cores 18 into thehollow body 8 depends substantially on the depth of the notches, and isat least identical thereto.

[0101] A flange 17, extending around each notch 16 and situated betweenthe two cylindrical cores 18, is pressed to close the sheet metal aroundthe cores in the area of the edge 9, and at the same time the notches 16are widened.

[0102] Therefore, the sheet metal in the area of the notches is pushedagainst the cores 18 and deformed plastically, thus assuming the curvedshape of the cores, as well seen in FIG. 8.

[0103] Afterwards, the cores 18 are withdrawn and the edge 9 is weldedalong the flange 17 of the widened notches 16, so as to obtain threeholes 21 separated from each other.

[0104] Possible finishing operations, moreover not necessary, will beperformed only on the flanges 17, slightly protruding due to thematerial brought by the welding.

[0105] At this point, it is possible to postpone the application of thefastening means 25 to the surfaces 3, 4 of the hollow body 8, only ifthe fastening means are formed by the outer threaded ring 26, andconsequently it is possible to treat a piece which is lighter andstructurally less rigid.

[0106] The holes 13 are coupled with the tubular elements 23 by a smallcylinder 24, introduced into each hole 13 and featuring a groove alongits circumference, into which a ring 34 of fusible material is inserted.

[0107] Then, the head of each tubular element 23 to be coupled is fittedonto the part of the small cylinder 24 protruding from the relative hole13.

[0108] The connection area between the tubular elements 23 and the headelement at the corresponding holes 13 and the ring 34 of the fusiblematerial, is heated by a flame carried rotating around the connectionarea.

[0109] The heat causes the fusion of the ring 34, thus welding the headelement to the tubular elements 23 by brazing.

[0110] The above described method allows the production of a headelement for heaters comprising only one hollow body 8 composed of a basewall 3, two opposite large sides 4, 5, joined to the base wall 3, twonarrow sides 14, 15, joined to the base wall 3 and integral with the twoopposite large sides 4, 5 and of holes 13, e.g. three, turned toward theinside of the hollow body 8.

[0111] A lateral through aperture 12, equipped with fastening means 25,is made on each of the opposite large sides 4, 5.

[0112] The hollow body 8 is obtained from one piece of sheet metal bydeep-drawing.

[0113] The holes 13 are delimited by an edge 9, shaped by cold stamping,which defines an open side 6, opposite to the base wall 3 of the hollowbody 8, with notches 16 made on the edge 9 and widened by cold stamping,so as to define the pressed flanges 17, which surround the notches 16and are welded to each other to separate the holes 13.

[0114] In the shown example, there are three holes 13, which need twonotches 16.

[0115] The fastening means 25 on each lateral through aperture 12 can bemade according to two embodiments.

[0116] According to a first embodiment, the fastening means 25 include athreaded ring fastened to the relative surface 4, 5.

[0117] According to the second embodiment, the fastening means 25 oneach lateral through aperture 12 are obtained by a circular crown 27surrounding the lateral through aperture 12, which has been plasticallydeformed by pressing outwards, so as to form a protruding edge 31.

[0118] A threaded ring 38 is introduced into the seat defined by theprotruding edge 31 and fixed therein either by welding spot or by slightdeformations made in the material of the head. Any other means can beused to fix the threaded ring and avoid rotation thereof.

[0119] Otherwise, the circular crown 27 is left free to be fastened toan adjacent head element by welding.

[0120] Consequently, the objects listed in the introduction have beenobtained by the method for producing head elements and the head elementdescribed above.

[0121] The head element is produced in a single body, by more pressingsteps, without the drawbacks resulting from the fusion procedure andwithout the necessity to weld two semi-shells to each other, or otherelements of considerable dimensions for the head element closing.

[0122] This feature allows to reduce the production time and costs andto obtain a product of high quality, yet using ferrous material, whichis cheap and easy to work.

[0123] The head element obtained by the above mentioned method isaesthetically pleasant, which allows to reduce as much as possible otherfinishing operations.

1. Method for producing head elements for heaters, characterized in thatit includes: preparing of a piece of a sheet metal (1); deep drawingsaid sheet metal piece (1) to obtain a hollow molded piece (2), definedby a base wall (3), sides (4,5,14,15) joined to and surrounding the basewall and forming an open side (6); cutting the sides (4,5,14,15) alongthe open side (6), to define a hollow body (8) with an edge (9), whichis uniform and extends around said open side (6); making a lateralthrough aperture (12) on two opposite sides (4,5) to obtain aperturedopposite sides; providing connection means (25) around each lateralthrough aperture (12); making of at least one notch (16), on theapertured opposite sides (4,5), along said edge (9); introducing atleast two cores (18) into said edge (9) matching areas (19) without saidat least one notch (16); stamping a flange (17) extending around each ofsaid at least one notch and included between said cores (18), so as toclose the sheet metal around said cores (18) and in the area of saidedge (9), thus widening said notches (16); removing said cores (18) fromthe hollow body; welding of said edge (9) along said flange (17) of saidwidened at least one notch (16), so as to obtain a series of holes (21)separated from each other.
 2. Method, according to claim 1,characterized in that the fastening means (25) are obtained on eachlateral through aperture (12) by welding a threaded ring (26) around thelateral through aperture (12).
 3. Method, according to claim 1,characterized in that the fastening means (25) are obtained on eachlateral through aperture (12) by pressing outwards a circular crown(27), extending around each lateral through aperture (12), so as to forma protruding edge (31) on each of said apertured sides (4,5).
 4. Method,according to claim 3, characterized in that a threaded ring (38) isplaced inside the seat defined by said protruding edge (31).
 5. Method,according to claim 3, characterized in that said outward pressing isobtained by inserting a flat core (28) into said hollow body (8),through the open side (6), before the holes (13) are made, with saidflat core (28) being equipped with a floating element (29), which issituated to match each lateral through aperture (12) and is pushedoutwards alternately in opposite directions, thus causing the forming ofthe protruding edge (31) on said circular crown (27), while on the outerpart of the hollow body (8) a die (30) is situated, to strike againstthe hollow body (8) and form the protruding edge 31 from outside. 6.Method, according to claim 1, characterized in that two notches (16),spaced from each other, are made on each of said apertured oppositesides (4,5), along said edge (9), to create three free areas (19), andthree cores are introduced into said edge (9) positioned to match saidfree areas (19).
 7. Method, according to claim 1, characterized in thatthe drawing of said metal sheet (1) in order to obtain said hollowmolded piece (2) includes a series of subsequent steps.
 8. Method,according to claim 1, characterized in that the coupling of the tubularelements (23) with said head element is obtained according to thefollowing steps: a small cylinder (24) is inserted into each hole (13),said small cylinder (24) having a groove made along its circumference,into which a ring (34) of fusible material is inserted; the head of eachtubular element (23) to be connected is fitted on the part of the smallcylinder (24) protruding from the relative hole (13); the connectionarea between each tubular element (23) and the head element near theholes (13) and the ring (34) of fusible material, is heated thus weldingthe head element and tubular elements (23) by brazing.
 9. A methodaccording to claim 1, wherein said apertured sides (4,5) are larger thanthe other non-apertured sides.
 10. A method for producing head elementsfor heaters, characterized in that it includes: preparation of a pieceof a sheet metal (1); deep drawing of said sheet metal (1) to obtain ahollow molded piece (2), defined by a base wall (3), sides (4,5,14,15)joined to and surrounding the base wall (3) and delimiting an open side(6); cutting the sides (4,5, 14,15) near said open side (6), to define ahollow body (8) with an edge (9), which is uniform and extends aroundsaid open side (6); making a lateral through aperture (12) on each twoopposite sides (4,5) to obtain two apertured opposite sides; making atleast one notch (16), on each of said apertured opposite sides (4,5),along said edge (9); introducing at least two cores (18) into said edge(9) in areas (19) without said at least one notch (16); pressing aflange (17) extending around said notches and included between saidcores (18), so as to close the sheet metal around said cores (18) and inthe area of said edge (9), thus widening said notches (16); removingsaid cores (18) from the hollow body; welding said edge (9) along saidflange (17) of said widened at least one notch (16), so as to obtainholes (21) separated from each other; providing fastening means (25) oneach lateral through aperture (12) on each of said apertured oppositesides (4,5).
 11. A method, according to claim 10, characterized in thatthe fastening means (25) on each lateral through aperture (12) areobtained by welding a threaded ring (26) around the lateral throughaperture (12).
 12. 9. A method according to claim 10, wherein saidapertured sides (4,5) are larger than the other non-apertured sides. 13.Head element for heaters, made in a single hollow body (8), defined by abase wall (3), sides (4,5, 14,15) joined to and surrounding the basewall (3), at least two holes (13) turned toward the inside of saidhollow body (8), with at least one lateral through aperture (12) made ontwo opposite sides (4,5) defining two apertured sides, characterized inthat: said body (8) is obtained from a single part of a deep-drawn metalsheet; said holes (13) are delimited by a press-shaped edge (9) of anopen side (6), opposite to said base wall (3) of said hollow body (8),with notches (16) made on said edge (9) and widened by pressing, so asto define pressed flanges (17), which surround the notches (16) and arewelded to each other to separate said holes (13); and fastening means(25) are provided on each lateral through aperture (12).
 14. Headelement, according to claim 13, characterized in that the fasteningmeans (25) on each lateral through aperture (12) are constituted by athreaded ring (26) fastened to a relative apertured side (4,5).
 15. Headelement, according to claim 13, characterized in that the fasteningmeans (25) on each lateral through aperture (12) include a circularcrown (27), surrounding the lateral through aperture (12) drawn outwardsto form a protruding edge (31).
 16. Head element, according to claim 15,characterized in that a threaded ring (38) is placed inside the seatdefined by said protruding edge (31).
 17. Head element, according toclaim 13, characterized in that notches (16), spaced apart andsurrounded by the molded flanges (17), are made on each of saidapertured opposite sides (4,5), along said edge (9), to delimit threeholes (13).
 18. Head element, according to claim 13, characterized inthat said apertured sides (4,5) are larger than the other non-aperturedsides.